Repeatability of Visual Acuity Measurement

Raasch, Thomas W.; Bailey, Ian L.; Bullimore, Mark A.

doi:10.1097/00006324-199805000-00024

Cited by 144 publications

(118 citation statements)

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“…Our repeatability scores using the CVA are slightly lower than that reported with ETDRS likely because our subjects were patients with clinical problems, while most ETDRS studies often tested young motivated optometry students without refractive errors. 22,23 Second, the ETDRS chart test and the CVA test are designed with different size steps; on an ETDRS-style chart each letter accounts for 0.02 logMAR in size, while the CVA uses 0.05 logMAR size steps. Random fluctuations in repeatability will lead to poorer repeatability of the CVA because of its coarser scale.…”

Section: Discussionmentioning

confidence: 99%

“…Random fluctuations in repeatability will lead to poorer repeatability of the CVA because of its coarser scale. 22,23 Third, letter-by-letter scoring (as measured using the ETDRS chart) is dependent upon the termination criteria of the examiner and whether the examined individual is forced to proceed through the entire chart to the end with encouraged guessing, 6 as opposed to proceeding downward to a line in which none of the letters are guessed correctly. 24 If the examiner knows the prior test result, this will influence his/her termination criteria.…”

Section: Discussionmentioning

confidence: 99%

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Visual function assessment in simulated real-life situations in patients with age-related macular degeneration compared to normal subjects

Barteselli¹,

Doede

et al. 2014

Eye

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Purpose To evaluate visual function variations in eyes with age-related macular degeneration (AMD) compared to normal eyes under different light/contrast conditions using a time-dependent visual acuity testing instrument, the Central Vision Analyzer (CVA). Methods Overall, 37 AMD eyes and 35 normal eyes were consecutively tested with the CVA after assessing best-corrected visual acuity (BCVA) using ETDRS charts. The CVA established visual thresholds for three mesopic environments (M1 (high contrast), M2 (medium contrast), and M3 (low contrast)) and three backlight-glare environments (G1 (high contrast, equivalent to ETDRS), G2 (medium contrast), and G3 (low contrast)) under timed conditions. Vision drop across environments was calculated, and repeatability of visual scores was determined. Results BCVA significantly reduced with decreasing contrast in all eyes. M1 scores for BCVA were greater than M2 and M3 (Po0.001); G1 scores were greater than G2 and G3 (Po0.01). BCVA dropped more in AMD eyes than in normal eyes between M1 and M2 (P ¼ 0.002) and between M1 and M3 (P ¼ 0.003). In AMD eyes, BCVA was better using ETDRS charts compared to G1 (Po0.001). The drop in visual function between ETDRS and G1 was greater in AMD eyes compared to normal eyes (P ¼ 0.004). Standard deviations of test-retest ranged from 0.100 to 0.139 logMAR. ConclusionThe CVA allowed analysis of the visual complaints that AMD patients experience with different lighting/contrast time-dependent conditions. BCVA changed significantly under different lighting/contrast conditions in all eyes, however, AMD eyes were more affected by contrast reduction than normal eyes. In AMD eyes, timed conditions using the CVA led to worse BCVA compared to non-timed ETDRS charts.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Visual function assessment in simulated real-life situations in patients with age-related macular degeneration compared to normal subjects

Barteselli¹,

Doede

et al. 2014

Eye

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“…In controlled laboratory conditions, Arditi & Caganello (1993) found that VA may, with a 95% confidence limit, be ascertained within logMAR AE 0.1 units in trained visually normal persons. In six different studies carried out with visually normal persons, using Sloan letters, with five letters per line and logMAR 0.1 line size progression, the random measurement error varied between 0.4 and 1.2 lines (Raasch et al 1998). Siderov & Tiu (1999) found that the 95% limits of agreement revealed logMAR AE 0.15 (2001) examined cataractous, pseudophakic and early-stage glaucoma eyes and found a Snellen acuity repeatability of logMAR AE 0.24 (95% limits of agreement) when examined letter by letter and logMAR AE 0.33 when expressed by lines.…”

Section: Discussionmentioning

confidence: 99%

“…Physical, physiological and psychological factors may influence VA measurement (Michaels 1975). Different optotypes, projectors and charts, different numbers of optotypes per line, and different line size progressions can cause variation in the results of VA measurements (Gibson & Sanderson 1980; Van den Brom et al 1995;Raasch et al 1998). The results of refractive error measurements (REM) are also subject to variation and thus can cause variation in VA results.…”

Section: Introductionmentioning

confidence: 99%

Random measurement error in visual acuity measurement in clinical settings

Leinonen

Laakkonen

Laatikainen

2005

Acta Ophthalmologica Scandinavica

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ABSTRACT.Purpose: To estimate the random measurement error in visual acuity (VA) determination in the clinical environment in cataractous, pseudophakic and healthy eyes. Methods: The VAs of patients referred for cataract surgery or consultation by ophthalmic professionals were re-examined and the VA results for distance using projector acuity charts were compared. Refractive errors were also remeasured. A total of 99 eyes (41 cataractous, 36 pseudophakic and 22 healthy eyes) were examined. The healthy comparison group consisted of hospital staff. Only one eye of each person and eyes with Snellen VAs of 0.3-1.3 (logMAR 0.52 to -0.11) were included. The mean time interval between the first and second examinations was 45 days. Results: The estimated standard deviation of measurement error (SDME) of repeated VA measurements of all eyes was logMAR 0.06. Eyes with the lowest VA (0.3-0.45) had the largest variability (SDME logMAR 0.09), and eyes with VA ‡ 0.7 had the smallest (SDME logMAR 0.04). The variability may be partly explained by the line size progression in lower VAs, partly by the difference in the remeasurement of the refractive error. The difference in the average VA between examinations 1 and 2 (logMAR 0.15 versus 0.12) was considered to be of some interest because it indicates that some learning effect is possible. Conclusion: Visual acuity results in clinical settings have a certain degree of inherent variability. In this series variability ranged from SDME logMAR 0.04 (eyes with good vision) to logMAR 0.09 (in the lower vision group) in the Snellen VA range of 0.3-1.3. Changes should be judged with caution, especially in cases of decreased VA.

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“…We measured binocular distance visual acuities of subjects using a Bailey-Lovie 3-meter logarithm of minimum angle of resolution (logMAR) acuity assessment chart [9]. We calculated the logMAR acuity scores using the per-letter method, which has demonstrated enhanced reliability over the per-line method in previous research [9][10][11]. The scores were then converted into a Snellenequivalent acuity score.…”

Section: Participantsmentioning

confidence: 99%

Recognition distance of pedestrian traffic signals by individuals with low vision

Williams¹,

Houten

Blasch³

2006

JRRD

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Abstract-Forty-one individuals with moderate-to-severe vision loss participated in a study to determine the minimum distance they required to correctly identify three different pedestrian traffic icon symbols, one of which was presented with an augmented light source. We found that subjects could identify the WALK icon without the augmented light source information, or animated eyes, from farther away than either the WALK icon with the augmented light source information or the DON'T WALK icon. These results differ from those of a previous study, which found that subjects could correctly identify the WALK icon with the augmented light source from a greater distance than the WALK or DON'T WALK icons without the augmented light source.

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Repeatability of Visual Acuity Measurement

Cited by 144 publications

References 0 publications

Visual function assessment in simulated real-life situations in patients with age-related macular degeneration compared to normal subjects

Visual function assessment in simulated real-life situations in patients with age-related macular degeneration compared to normal subjects

Random measurement error in visual acuity measurement in clinical settings

Recognition distance of pedestrian traffic signals by individuals with low vision

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